This invention relates to data transmission and in particular to improved means and methods for transmitting and receiving a plurality of digital data signals over a single transmission line.
Computer systems often involve a plurality of units such as processors, memories and input-output devices which are located some distance apart and are connected by transmission lines, such as electrical cables. Since a considerable number of interconnections are required between such units, the cost, complexity and space requirements of the transmission lines interconnecting the units are substantial. These problems can be reduced by using each transmission line to carry as many data signals as is deemed to be practical. Also, it is of a advantage that the communication system by such as to permit the data signals to be transmitted and received asynchronously with respect to one another, and also, without the need for incorporating additional clocking in the transmitted signal for use in decoding the received signal.